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  <title>Document</title>
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<script>
  Test.prototype.getName = function() {
    console.log(this.name)
  }
  function Test(name) {
    this.name = name
    this.getName = function() {
      console.log(this.name)
      return 2
    }
  }
  function Demo(name, age) {
    Test.call(this, name)
  }
  const demo = new Demo('zhangli', '21')
  console.log(demo.getName())
</script>
</html>